title: Characterisation and expression of calpain family members in relation to nutritional status, diet composition and flesh texture in gilthead sea bream (Sparus aurata).
abstract: Calpains are non-lysosomal calcium-activated neutral proteases involved in a wide range of cellular processes including muscle proteolysis linked to post-mortem flesh softening. The aims of this study were (a) to characterise several members of the calpain system in gilthead sea bream and (b) to examine their expression in relation to nutritional status and muscle tenderisation. We identified the complete open reading frame of gilthead sea bream calpains1-3, sacapn1, sacapn2, sacapn3, and two paralogs of the calpain small subunit1, sacapns1a and sacapns1b. Proteins showed 63-90% sequence identity compared with sequences from mammals and other teleost fishes, and the characteristic domain structure of vertebrate calpains. Transcripts of sacapn1, sacapn2, sacapns1a and sacapns1b had a wide tissue distribution, whereas sacapn3 was almost exclusively detected in skeletal muscle. Next, we assessed transcript expression in skeletal muscle following alteration of nutritional status by (a) fasting and re-feeding or (b) feeding four experimental diets with different carbohydrate-to-protein ratios. Fasting significantly reduced plasma glucose and increased free fatty acids and triglycerides, together with a significant increase in sacapns1b expression. Following 7 days of re-feeding, plasma parameters returned to fed values and sacapn1, sacapn2, sacapns1a and sacapns1b expression was significantly reduced. Furthermore, an increase in dietary carbohydrate content (11 to 39%) diminished growth but increased muscle texture, which showed a significant correlation with decreased sacapn1 and sacapns1a expression, whilst the other calpains remained unaffected. This study has demonstrated that calpain expression is modulated by nutritional status and diet composition in gilthead sea bream, and that the expression of several calpain members is correlated with muscle texture, indicating their potential use as molecular markers for flesh quality in aquaculture production.
authors.affiliation: Department of Physiology and Immunology, Faculty of Biology, University of Barcelona, Barcelona, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Salmerón
authors.forename: Daniel
authors.initials: D
authors.lastname: García de la serrana
authors.forename: Vanesa
authors.initials: V
authors.lastname: Jiménez-Amilburu
authors.forename: Ramón
authors.initials: R
authors.lastname: Fontanillas
authors.forename: Isabel
authors.initials: I
authors.lastname: Navarro
authors.forename: Ian A
authors.initials: IA
authors.lastname: Johnston
authors.forename: Joaquim
authors.initials: J
authors.lastname: Gutiérrez
authors.forename: Encarnación
authors.initials: E
authors.lastname: Capilla
mesh_terms: D000704:Analysis of Variance; D000824:Animal Nutritional Physiological Phenomena / Q000502:physiology*; D000818:Animals; D017756:Aquaculture; D001483:Base Sequence; D001786:Blood Glucose / Q000032:analysis; D002154:Calpain / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D004032:Diet; D004040:Dietary Carbohydrates / Q000494:pharmacology; D005227:Fatty Acids / Q000097:blood; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D008460:Meat / Q000592:standards*; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000378:metabolism; D016366:Open Reading Frames / Q000235:genetics; D021122:Protein Subunits / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D021541:Sea Bream / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D017385:Sequence Homology
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D005227:Fatty Acids; D021122:Protein Subunits; D002154:Calpain